Alkali metal-containing composite metal oxides are useful compounds. For example, lithium composite metal oxides are used for electrodes for lithium-ion secondary batteries, and potassium composite metal oxides are used for friction materials. For example, lithium-cobalt composite oxides, lithium-nickel composite oxides, lithium-manganese composite oxides, lithium-manganese-cobalt composite oxides, and lithium-nickel-cobalt composite oxides are used as positive electrode active materials of lithium-ion secondary batteries. For example, lithium titanate composite oxides are used as negative electrode active materials. For example, K2O.6 (TiO2) and K2O.8 (TiO2) are used for friction materials.
These alkali metal-containing composite metal oxides are produced by putting powder of a production raw material for producing an alkali metal-containing composite metal oxide into a calcining member such as a sagger or a crucible (setter) for calcining. In general, alumina, magnesia, zirconia, mullite, cordierite, and the like are used for calcining members. It is necessary, however, to select a calcining member having low reactivity and high durability because alkali metals are corrosive. For example, JP-A-2004-63261 (Patent Document 1) discloses a refractory for calcining made of alumina, mullite, and/or cordierite, which contains lithium and cobalt, in which the lithium content is 2 to 5% by mass and the cobalt content is 2 to 5% by mass.
JP-A-2003-146658 (Patent Document 2) discloses a method of producing a composite oxide, in which a sheet material made of a material to be carbonized is sandwiched between a container and a calcining raw material powder to perform calcining.